Endless track and a manufacturing method thereof

ABSTRACT

An endless track includes an iron link belt, a continuous pad, and a connecting device. The iron link belt includes a link unit assembly constructed of a plurality of link units connected to each other. Each link unit includes a pair of links. The iron link belt may include a plate welded to the pair of links and extending perpendicularly to a direction in which the link unit assembly extends. The continuous pad includes the same number of core metal plates as that of the link units, and a single rubber belt covering and being vulcanization-adhered to a ground opposing surface of each of the core metal plates. The rubber belt extends continuously over all of the core metal plates. The rubber belt may include a small thickness portion positioned between two adjacent core metal plates. The connecting device connects the iron link belt and the continuous pad.

This application is based on and claims priority from Japanese PatentApplication Nos. 2000-79997, 2000-173699 and 2001-42920 filed on Mar.22, 2000, Jun. 9, 2000 and Feb. 20, 2001, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endless track of the type having aground opposing surface made from rubber and a manufacturing methodthereof.

2. Description of Related Art

Various types of endless tracks used for construction vehicles areknown, some of which include a ground opposing surface made from rubberfor protecting road surfaces.

Such conventional endless tracks of the type having a ground opposingsurface made from rubber are grouped into the following threecategories:

The first category of the conventional endless track includes an ironlink belt 1, an iron shoe 2 and a rubber pad (A-Type) 3, as illustratedin FIG. 14. The iron link belt 1 is provided with the iron shoe 2 whichis formed independently of the iron link belt 1. Each iron shoe 2 isprovided with the rubber pad (A-Type) 3 including an iron plate 3 a anda rubber material 3 b, which is adhered to the iron plate 3 a through avulcanization process.

The second category of the conventional endless track includes an ironlink belt 1 and a rubber pad (B-Type) 4, as illustrated in FIG. 15. Theiron link belt 1 includes a pair of links, to which a plate 4 c iswelded. The plate 4 c is fastened to the rubber pad (B-Type) by a boltor the like. The rubber pad (B-Type) includes a core metal plate 4 a,and a rubber material 4 b, which is adhered to the core metal plate 4 athrough a vulcanization process. The rubber pad (B-type) is directlyfixed to the iron link belt 1 without employing an iron shoe. Therefore,the endless track of the second type does not include an iron shoe.

The third category of the conventional endless track includes a rubbercrawler 5, as illustrated in FIG. 16. A plurality of iron core plates 5a are embedded in a single rubber belt 5, and the rubber 5 b of therubber belt 5 is adhered to the iron core plates 5 a through avulcanization process, while exposing a part of each iron core plate 5a. The rubber belt 5 b extends endlessly. The endless track engages asprocket at an exposed portion of each iron core plate 5 a. Therefore,the endless track of the third category includes neither an iron linkbelt nor an iron shoe.

Hereinafter, the first category of the conventional endless track willbe referred to hereafter as a rubber pad type A, the second category ofthe endless track will be referred to hereafter as a rubber pad type B,and the third category of the endless track will be referred tohereafter as a rubber crawler type.

The following problems exist in the conventional endless tracks of thetype having the ground opposing surface made from rubber.

With the conventional endless track of the rubber pad type A (the firstcategory), rubber needs to be vulcanization-adhered to the iron plateper each of the rubber pads, which requires much time and work,resulting in low productivity.

Further, the conventional endless track of the rubber pad type Arequires a large number of members. Thus, the cost is high.

Similarly, with the conventional endless track of the rubber pad type B(the second category), rubber needs to be vulcanization-adhered to thecore plate per each of the rubber pads, which requires much time andwork, resulting in low productivity.

Although the number of members required for the rubber pad type B issmaller than that of the rubber pad type A because no shoes are includedin the rubber pad type B, the rigidity is required all over the rubberpad, so that the manufacturing cost is almost the same as that of theconventional endless track of rubber pad type A.

With the conventional endless track of the rubber crawler type (thethird category), the number of the members and the cost are reducedcompared with those of the rubber pad type A and the rubber pad type B.However, because a tensile force is borne by the rubber belt only, thelife of the rubber belt is relatively short. As a result, breakage ofthe rubber belt and derailment of the rubber belt are likely to occurduring operation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an endless track of thetype having a ground opposing surface made from rubber and amanufacturing method thereof, whereby the productivity invulcanization-forming may be improved, the number of members may bereduced, and the durability may be improved.

The above object can be performed by an endless track and amanufacturing method according to the present invention, as follows:

An endless track includes an iron link belt, a continuous pad and aconnecting device. The iron link belt includes a link unit assemblyconstructed of a plurality of link units connected to each other. Eachlink unit includes a pair of links.

The continuous pad includes the same number of core metal plates as thatof the plurality of link units and a single rubber belt. Each of thecore metal plates is fixed to each of the plurality of link units. Therubber belt covers and is vulcanization-adhered to a ground opposingsurface of each of the core metal plates. The rubber belt extendscontinuously over all of the core metal plates.

The connecting device connects the iron link belt and the continuous padat the link units and the core metal plates.

Each of the pair of links comprises at least one of a bent plate linkand a forged link.

The connecting device includes at least one of a bolt-and-nut and awelding.

The connecting device includes the bolt-and-nut, and the bolt-and-nut iswelded to the core metal plate and is covered with the rubber of therubber belt.

Preferably, the iron link belt includes the same number of plates asthat of the plurality of link units. Each of the plates is welded to thepair of links of each of the plurality of link units of the link unitassembly and extends perpendicularly to a direction in which the linkunit assembly extends. Each of the core metal plates of the continuouspad is fixed to each of the plates of the iron link belt. The rubberbelt of the continuous pad includes a small thickness portion betweentwo adjacent core metal plates of the core metal plates. The link beltand the continuous pad are connected to each other by the connectingdevice at the plates and the core metal plates.

Preferably, each of the core metal plates of the continuous pad extendsperpendicularly to a direction in which the link unit assembly extendsand is directly welded to the pair of links of each of the plurality oflink units of the link unit assembly.

The rubber belt of the continuous pad includes a small thickness portionpositioned between two adjacent core metal plates of the core metalplates.

Preferably, the iron link belt includes the same number of plates asthat of the plurality of link units. Each of the plates is welded to thepair of links of each of the plurality of link units of the link unitassembly and extends perpendicularly to a direction in which the linkunit assembly extends. Each of the core metal plates of the continuouspad is fixed to each of the plates of the iron link belt. The rubberbelt of the continuous pad includes a normal thickness portionpositioned between two adjacent core metal plates of the core metalplates. The link belt and the continuous pad are connected to each otherby the connecting device at the plates and the core metal plates.

Preferably, each of the core metal plates of the continuous pad extendsperpendicularly to a direction in which the link unit assembly extendsand is directly welded to the pair of links of each of the plurality oflink units of the link unit assembly. The rubber belt of the continuouspad includes a normal thickness portion positioned between two adjacentcore metal plates of the core metal plates.

A method for manufacturing an endless track includes: (a) connecting aplurality of link units each having a pair of links therebymanufacturing a link unit assembly of an iron link unit; and (b)providing the same number of core metal plates as that of the pluralityof link units of the iron link belt and forming a single rubber beltcontinuously extending over all of the core metal plates such that thesingle rubber belt covers and is vulcanization-adhered to a groundopposing surface of each of the core metal plates, thereby manufacturinga continuous pad.

Each link of the pair of links is manufactured through at least one of abending and forging process.

Preferably, during the manufacturing of the iron link belt, a plateextending perpendicularly to a direction in which the link unit assemblyextends is welded to the pair of links of each of the plurality of linkunits of the link unit assembly. During the manufacturing of thecontinuous pad, before the core metal plates are fixed to the pluralityof link units, a small thickness portion is formed between two adjacentcore metal plates of the core metal plates when the rubber belt isvulcanization-formed. After manufacturing the continuous pad, the ironlink belt and the continuous pad are connected to each other by aconnecting device at the plates and the core metal plates.

Preferably, the connecting device includes a bolt and a nut, and beforevulcanization-forming of the rubber belt, at least one of the bolt andthe nut is welded to each of the core metal plate. Duringvulcanization-forming of the rubber belt, at least one of the bolt andthe nut is covered with a rubber of the rubber belt.

Preferably, each of the core metal plates extending perpendicularly to adirection in which the link unit assembly extends is directly welded tothe pair of links of each of the plurality of link units of the linkunit assembly of the iron link belt. During manufacturing of thecontinuous pad, when the rubber belt is vulcanization-formed, a smallthickness portion is formed to the rubber belt between two adjacent coremetal plates of the core metal plates.

Preferably, during manufacturing of the iron link belt, a plateextending perpendicularly to a direction in which the link unit assemblyextends is welded to the pair of links of each of the plurality of linkunits of the link unit assembly. Before manufacturing the continuouspad, each of the core metal plates is fixed to the plate of each of thelink units of the iron link belt. During manufacturing of the continuouspad, the rubber belt is vulcanization-formed such that the rubber beltcovers each of the core metal plates and such that a normal thicknessportion is formed to the rubber belt between two adjacent core metalplates of the core metal plates when the rubber belt isvulcanization-formed.

Preferably, each of the core metal plates extending perpendicularly to adirection in which the link unit assembly extends is directly welded tothe pair of links of each of the plurality of link units of the linkunit assembly of the iron link belt. During manufacturing of thecontinuous pad, a normal thickness portion is formed to the rubber beltbetween two adjacent core metal plates of the core metal plates when therubber belt is vulcanization-formed.

Preferably, the method further includes dividing the rubber belt betweentwo adjacent core metal plates of the core metal plates among aplurality of separate pads.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentinvention will become more apparent and will be more readily appreciatedfrom the following detailed description of the preferred embodiments ofthe present invention in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a partial side view of an endless track, according to a firstembodiment of the present invention;

FIG. 2 is a partial plan view of the endless track, as viewed from aside opposite to a ground opposing surface, according to the firstembodiment of the present invention;

FIG. 3 is a partial side view illustrating a manufacturing method of theendless track shown in a manufacturing order, according to the firstembodiment of the present invention;

FIG. 4 is a partial side view of an endless track, according to a secondembodiment of the present invention;

FIG. 5 is a partial plan view of the endless track, as viewed from aside opposite to a ground opposing surface, according to the secondembodiment of the present invention;

FIG. 6 is a partial side view illustrating a manufacturing method of theendless track shown in a manufacturing order, according to the secondembodiment of the present invention;

FIG. 7 is a partial side view of an endless track, according to a thirdembodiment of the present invention;

FIG. 8 is a partial plan view of the endless track, as viewed from aside opposite to a ground opposing surface, according to the thirdembodiment of the present invention;

FIG. 9 is a side view illustrating a manufacturing method of the endlesstrack shown in a manufacturing order, according to the third embodimentof the present invention;

FIG. 10 is a partial side view of an endless track, according to afourth embodiment of the present invention;

FIG. 11 is a partial plan view of the endless track, as viewed from aside opposite to a ground opposing surface, according to the fourthembodiment of the present invention;

FIG. 12 is a side view illustrating a manufacturing method of theendless track shown in a manufacturing order, according to the fourthembodiment of the present invention;

FIG. 13 is a side view of an endless track, applicable to any one of theembodiments of the present invention;

FIG. 14 is a partial side view of a conventional endless track of arubber pad type A;

FIG. 15 is a partial side view a conventional endless track of a rubberpad type B; and

FIG. 16 is a partial perspective view of a conventional endless track ofa rubber crawler type.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment of the present invention is directed to an endlesstrack having a plate and a small thickness portion, and to amanufacturing method thereof, as illustrated in FIGS. 1-3.

Each of the second, third and fourth embodiments of the presentinvention is directed to an endless track and a manufacturing methodpartially changed from the first embodiment, respectively.

The second embodiment of the present invention is directed to an endlesstrack having no plate and having a small thickness portion, and to amanufacturing method thereof, as illustrated in FIGS. 4-6.

The third embodiment of the present invention is directed to an endlesstrack having a plate and having no small thickness portion, and to amanufacturing method thereof, as illustrated in FIGS. 7-9.

The fourth embodiment of the present invention is directed to an endlesstrack having no plate and having no small thickness portion, and to amanufacturing method thereof, as illustrated in FIGS. 10-12.

FIG. 13 illustrates an endless track applicable to any of theembodiments of the present invention.

Structural portions common to or similar to all of embodiments of thepresent invention are denoted with the same reference numeralsthroughout all of the embodiments of the present invention.

First, structures and effects common to or similar to all of theembodiments of the present invention will be explained with reference toFIGS. 1-3.

An endless track 100 includes an iron link belt 10, a continuous pad 20,and a connecting device 30.

The iron link belt 10 includes a link unit assembly 11 constructed of aplurality of link units 12 connected to each other. Each of the linkunits 12 includes a pair of links 13.

The plurality of link units 12 are connected to each other by pins 15and bushings 14 to be formed into the link unit assembly 11.

The link 13 may be a link manufactured by bending a rolled steel plate(hereinafter, a bent plate link), or may be a link manufactured byforging (hereinafter, a forged link).

In the case of the bent plate link, an intermediate portion of the link13 extends obliquely relative to opposite ends of the link 13.

The continuous pad 20 includes the same number of core metal plates 21as that of the plurality of link units 12, and a single rubber belt 24.Each of the core metal plate 21 is fixed to each of the plurality oflink units 12. The rubber belt 24 covers and is vulcanization-adhered toa ground opposing surface of each of the core metal plates 21 andextends continuously over all of the core metal plates 21. A slit 27 maybe provided in an intermediate portion in a width direction of therubber belt 24, which is a portion corresponding to a connected portionof adjacent links in a longitudinal direction of the rubber belt 24, soas to avoid interference with the link 13.

The connecting device 30 connects the iron link belt 10 and thecontinuous pad 20 at the link units 12 and the core metal plates 21.

The connecting device 30 includes either a bolt-and-nut 31, 32 or awelding. In a case where the connecting device 30 includes thebolt-and-nut 31, 32, either the bolt or the nut is fixed to the coremetal plate 21 by welding and is covered with the rubber of the rubberbelt 24.

The manufacturing method of the endless track 100 of the presentinvention includes: connecting a plurality of link units 12 each havinga pair of links 13 thereby manufacturing the link unit assembly 11 ofthe iron link belt 10; and providing the same number of core metalplates 21 as that of the plurality of link units 12 of the iron linkbelt 10 and forming the single rubber belt 24 continuously extendingover all of the core metal plates 21 such that the single rubber belt 24covers and is vulcanization-adhered to the ground opposing surface ofeach of the core metal plates 21, thereby manufacturing a continuous pad20.

Each of the pair of links 13 is manufactured by bending or forging.

Effects of the endless track 100 and the manufacturing method thereofaccording to the present invention will be explained below.

Since the vulcanization-forming of the single rubber belt 24 to which aseries of core metal plates 21 is embedded is performed simultaneously,the productivity is greatly improved as compared with the conventionalendless tracks of the rubber pad type A and the rubber pad type B inwhich vulcanization-adhesion of the rubber to each of the core metalplates is performed as many times as the number of the rubber pads.

Further, since the series of core metal plates 21 is embedded to thesingle rubber belt 24, the number of members required is smaller thanthat of the conventional endless tracks of the rubber pad type A and therubber pad type B in which a plurality of rubber pads (core metal plateswith rubber) need to be manufactured.

As discussed above, since the productivity improves by performingvulcanization-forming of the rubber belt 24 simultaneously and thenumber of members is reduced, the manufacturing cost of the endlesstrack is reduced to nearly the same level as that of the conventionalrubber crawler type.

Further, since the iron link belt 10 bears the tensile force of theendless track, the durability problem with the conventional endlesstrack of rubber crawler type is completely eliminated. Thus, durabilitysubstantially the same as the conventional endless tracks of the rubberpad type A and rubber pad type B can be obtained.

Next, structures and effects unique to each embodiment of the presentinvention will be explained.

In the endless track 100 and the manufacturing method thereof accordingto the first embodiment of the present invention, as illustrated inFIGS. 1-3, the iron link belt 10 includes a plate 16, and the rubberbelt 24 includes a small thickness portion 25.

More particularly, the iron link belt 10 includes the link unit assembly11 and the plates 16. Each of the plates 16 is fixed to the pair oflinks 13 of each of the link units 12 of the link unit assembly 11 bywelding 17. The plate 16 is constructed of a rectangular steel plateextending perpendicularly to a direction in which the link unit assembly11 extends. The number of the plates 16 is the same as that of the linkunits 12. Two bolt-holes 18 are respectively formed on each side of theplate 16 located outside the pair of the link 13. A mud hole(mud-ejection hole) 19 may be formed in the central portion of the plate16. The mud hole 19 may not necessarily be formed therein.

The continuous pad 20 includes the core metal plates 21 and the rubberbelt 24. Each of the core metal plate 21 is constructed of a steel plateand is fixed to each of the plates 16 of the iron link belt 10. Thenumber of the core metal plates 21 is the same as that of the plates 16.Each of the core metal plates 21 includes bolt-holes 22 disposed inpositions corresponding to the bolt-holes 18 of the plate 16. A mud hole23 may be formed in the central portion of the core metal plate 21. Themud hole 23 may not necessarily be formed therein.

The rubber belt 24 is constructed of a single rubber belt and extendscontinuously over all of the core metal plates 21 of the same number asthat of the plates 16. The rubber belt 24 includes the small thicknessportion 25 positioned between two adjacent core metal plates of the coremetal plates 21. The small thickness portion 25 constitutes a part ofthe rubber belt 24. The small thickness portion 25 includes no coremetal plate 21, and the thickness of the continuous pad 20 at the smallthickness portion is thinner than that at a portion provided with thecore metal plate and having a normal thickness. Preferably, thethickness of the rubber belt 24 at the small thickness portion is lessthan one third of that at the normal thickness portion, and is, morepreferably, less than one fourth thereof. When the small thicknessportion of the endless track 100 reaches a straight portion, the smallthickness portion 25 may be curved or loosened perpendicularly to adirection in which the rubber belt 24 extends. A surface of the coremetal plate 21 opposed to the plate 16 is exposed from the rubber belt24 and the core plate 21 thus can contact the plate 16 directly. A mudhole 26 may be disposed in the rubber belt 24 at a portion correspondingto the mud hole 23 of the core metal plate 21. The mud hole 26 may notnecessarily be formed therein. Preferably, a slit 27 is provided in anintermediate portion in a width direction of the rubber belt 24, whichis a portion corresponding to a connected portion of adjacent links in alongitudinal direction of the rubber belt 24, so as to avoidinterference with the link 13.

The reason for disposing the small thickness portion 25 will beexplained. In the state where the endless track 100 is mounted on theconstruction vehicle, the length of the iron link belt and the rubberbelt equals each other when the endless track 100 is at a straightportion. The length of the rubber belt becomes longer than that of theiron link belt in proportion to a radial distance from a rotationalcenter when the endless track 100 is positioned around the sprocket. Inorder to smoothly absorb the length differential, the small thicknessportion is disposed to allow the rubber belt 24 to be easily extended.In a case where the small thickness portion 25 has a loosened portionwhen the endless track 100 is at a straight portion, the loosenedportion is deformed to extend when the track 10 reaches the sprocket, sothat the length differential between the iron link belt and the rubberbelt can be absorbed more easily.

The connecting device 30 is a means for connecting the iron link belt 10and the continuous pad 20 at the plate 16 and the core metal plate 21.The connecting device 30 includes a bolt 31 and a nut 32. Either thebolt 31 or the nut 32 (the bolt 31 is shown as the connecting device 30in the drawings) is welded to the core metal plate 21 beforevulcanization-forming of the rubber belt 24, and is covered with rubberat the time of vulcanization- forming.

The manufacturing method of the endless track according to the firstembodiment of the present invention includes: manufacturing the ironlink belt 10, manufacturing the continuous pad 20, and connecting theiron link belt 10 and the continuous pad 20. Either manufacturing theiron link belt 10 or manufacturing the continuous pad 20 may beconducted earlier.

During the manufacturing of the iron link belt 10, the plate 16extending perpendicularly to a direction in which the link unit assembly11 extends is welded to the pair of link units 13 of each of the linkunits 12 of the link unit assembly 11.

During the manufacturing of the continuous pad 20, the rubber belt 24 isvulcanization-formed before the core metal plates 21 are fixed to thelink units 12. When the rubber belt 24 is vulcanization-formed, thesmall thickness portion 25 is formed between two adjacent core metalplates of the core metal plates 21 of the rubber belt 24.

After manufacturing the continuous pad 20, the iron link belt 10 and thecontinuous pad 20 are connected to each other by the connecting device30 at the plates 16 and the core metal plates 21.

The connecting device 30 includes the bolt 31 and the nut 32. Either thebolt 31 or the nut 32 (the bolt 31 is shown as the connecting device 30in the drawings) is welded to the core metal plates 21 beforevulcanization-forming of the rubber belt 24 and is covered with rubberof the rubber belt 24 during vulcanization-forming of the rubber belt24. When connecting the iron link belt 10 and the continuous pad 20, thebolt 31 is inserted through the bolthole 18 and is threaded with the nut32 thereby fixing the plate 16 and the core metal plate 21.

With the effects of the endless track and the manufacturing methodthereof according to the first embodiment of the present invention,since the continuous pad 20 includes the small thickness portion 25, thelength differential between the continuous pad 20 and the iron link belt10 can be smoothly absorbed when the endless track 100 moves from astraight portion of the construction vehicle to a semi-circular portionaround the sprocket. As a result, the tensile deformation and thetensile stress are not generated in the rubber belt 24, which ensuresgood durability. Further, since the plate 16 is welded to the pair oflinks 13 and the plate 16 and the core metal plate 21 are connected bythe connecting device 30, the iron link belt 10 and the continuous pad20 can be manufactured independently of each other. Therefore, eithermanufacturing the iron link belt 10 or manufacturing the continuous pad20 may be manufactured earlier, resulting in a high degree of freedom inmanufacturing processes.

In the endless track 100 and the manufacturing method thereof accordingto the second embodiment of the present invention, as illustrated inFIGS. 4-6, the iron link belt 10 includes no plate 16, and the rubberbelt 24 includes the small thickness portion 25.

More particularly, the pair of links 13 of each of the link units 12 ofthe link unit assembly 11 of the iron link belt 10 is fixed to each ofthe core metal plates 21 of the continuous pad 20 by a welding 17.

The continuous pad 20 includes the core metal plates 21 and the rubberbelt 24. Each of the core metal plates 21 is constructed of arectangular plate extending perpendicularly to a direction in which thelink unit assembly 11 extends. The number of the core metal plates 21 isthe same as that of the link units 12. A mud hole 23 may be formed inthe central portion of the core metal plate 21. The mud hole 23 may notnecessarily be formed therein.

The rubber belt 24 is continuous over all of the core metal plates 21 ofthe same number as that of the link units 12. The rubber belt 24includes the small thickness portion 25 positioned between two adjacentcore metal plates of the core metal plates 21. The small thicknessportion 25 constitutes a part of the rubber belt 24. The small thicknessportion 25 includes no core metal plate 21 and the thickness of thecontinuous pad 20 at the small thickness portion 25 is thinner than thatat the normal thickness portion provided with the core metal plate 21.

Preferably, the thickness of the rubber belt 24 at the small thicknessportion is less than one third of that at the normal thickness portion,and is, more preferably, less than one fourth thereof. When the smallthickness portion 25 of the endless track 100 reaches a straightportion, the small thickness portion 25 may be curved or loosenedperpendicularly to a direction in which the rubber belt 24 extends. Asurface of the core metal plate 21 opposed to the link unit 12 isexposed from the rubber belt 24. Thus, the core plate 21 directlycontacts the link 13 and is welded thereto. The mud hole 26 may bedisposed in the rubber belt 24 at a portion corresponding to the mudhole 23 of the core metal plate 21. The mud hole 26 may not necessarilybe formed therein.

The reason for disposing the small thickness portion 25 will beexplained. In the state where the endless track 10 is mounted on theconstruction vehicle, the length of the iron link belt and that of therubber belt equals each other while the endless track 100 is positionedat a straight portion, the length of the rubber belt becomes longer thanthat of the iron link belt in proportion to a radial distance from arotational center when the endless track 100 is positioned around thesprocket. The rubber belt 24 is easily extended at the small thicknessportion 25 to allow the length differential to be smoothly absorbed.

The manufacturing method of the endless track according to the secondembodiment of the present invention includes: manufacturing the ironlink belt 10; manufacturing the continuous pad 20; and connecting theiron link belt 10 and the continuous pad 20.

During the manufacturing of the iron link belt 10, the core metal plate21 of the continuous pad 20 is welded to the pair of links 13 of each ofthe link units 12 of the link unit assembly 11.

During the manufacturing of the continuous pad 20, the rubber belt 24 isvulcanization-formed. When the rubber belt 24 is vulcanization-formed,the small thickness portion 25 is formed between two adjacent core metalplates of the core metal plates 21 of the rubber belt 24.

With the effects of the endless track and the manufacturing methodthereof according to the second embodiment of the present invention,since the continuous pad 20 includes the small thickness portion 25, thelength differential between the continuous pad 20 and the iron link belt10 can be smoothly absorbed when the endless track 100 moves from thestraight portion of the construction vehicle to a semi-circular portionaround the sprocket. As a result, the tensile deformation and thetensile stress are not generated in the rubber belt 24, which ensuresgood durability. Further, since the core metal plate 21 is welded to thepair of links 13, the plate 16 of the iron link unit 10 can be removed,which leads to the reduction in the number of members and in themanufacturing cost.

In the endless track 100 and the manufacturing method thereof accordingto the third embodiment of the present invention, as illustrated inFIGS. 7-9, the iron link belt 10 includes a plate 16, and the rubberbelt 24 includes no small thickness portion 25.

More particularly, the iron link unit 10 includes the link unit assembly11 and the plates 16. Each of the plates 16 is fixed to the pair oflinks 13 of each of the link units 12 of the link unit assembly 11 ofthe iron link belt 10 by the welding 17. The plate 16 is constructed ofa rectangular steel plate extending perpendicularly to a direction inwhich the link unit assembly 11 extends. The number of the plates 16 isthe same as that of the link units 12. Two boltholes 18 are respectivelyformed on each side of the plate 16 located outside the pair of links13. A mud hole 19 may be formed in the central portion of the plate 16.The mud hole 19 may not necessarily be formed therein.

The rubber belt 24 is constructed of a single rubber belt and iscontinuous over all of the core metal plates 21 of the same number asthat of the plates 16. The rubber belt 24 includes no small thicknessportion 25, which means that the rubber belt 24 has the normal thicknessportion between adjacent core metal plates 21. A surface of the coremetal plate 21 opposed to the plate 16 is exposed from the rubber belt24, and the core plate 21 thus directly contacts the plate 16. The mudhole 26 may be disposed in the rubber belt 24 at a portion correspondingto the mud hole 23 of the core metal plate 21. The mud hole 26 may notnecessarily be formed therein.

The connecting device 30 is a means for connecting the iron link belt 10and the continuous pad 20 at the plates 16 and the core metal plates 21and includes the bolt 31 and the nut 32. Either the bolt 31 or the nut32 (the bolt 31 is shown as the connecting device 30 in the drawings) iswelded to the core metal plate 21 before the rubber belt 24 isvulcanization-formed, and is covered with rubber at the time ofvulcanization-forming the rubber belt 24.

In the manufacturing method of the endless track according to the thirdembodiment of the present invention, during manufacturing the iron linkbelt 10, the plate 16 extending perpendicularly to a direction in whichthe link unit assembly 11 extends is welded to the pair of link units 13of each of the plurality of link units 12 of the link unit assembly 11.Before manufacturing the continuous pad 20, each of the core metal plate21 is fixed to each of the plates 16 of each of the link units 12 of thelink unit assembly 12. During the manufacturing of the continuous pad20, the rubber belt 24 is vulcanization-formed such that the rubber belt24 covers each of the core metal plates 21 and such that no smallthickness portion 25 is formed in the rubber belt 24 between twoadjacent core metal plates of the core metal plates 21 when the rubberbelt is vulcanization-formed.

The plate 16 and the core metal plates are connected to each other bythe connecting device 30. The connecting device 30 includes the bolt 31,which is inserted into the bolthole formed in the core metal plate 21.

With the effects of the endless track and the manufacturing methodthereof according to the third embodiment of the present invention,since the rubber belt 24 includes no small thickness portion 25, whenthe rubber belt 24 reaches the sprocket of the construction vehicle, agreater force is required for causing the rubber belt 24 to extendbetween adjacent core metal plates 21 than in the first and the secondembodiments of the present invention.

After the rubber belt 24 is vulcanization-formed such that the rubberbelt extends continuously over all of the core metal plates 21, therubber belt 24 may be divided or cut between two adjacent core metalplates of the core metal plates 21 into a plurality of separate pads. Insuch a case, the manufacturing efficiency obtained by continuouslyforming the rubber belt 24 over all of the core metal plates 21 can beimproved, as compared with the conventional endless track in which therubber pad is vulcanization-formed per each of the core metal plates 21.

In the endless track 100 and the manufacturing method thereof accordingto the fourth embodiment of the present invention, the iron belt link 10includes no plate 16, and the rubber belt 24 includes no small thicknessportion 25.

More particularly, the pair of link units 13 of each of the plurality oflink units 12 of the link unit assembly 11 is fixed to each of the coremetal plates 21 of the continuous pad 20 by the welding 17.

The continuous pad 20 includes the core metal plates 21 and the rubberbelt 24. Each of the core metal plates 21 is constructed of arectangular steel plate extending perpendicularly to the direction inwhich the link unit assembly 11 extends. The number of the core metalplates 21 is the same as that of the link units 12. The mud hole 23 maybe formed in the central portion of the core metal plate 23. The mudhole 23 may not necessarily be formed therein.

The rubber belt 24 is constructed of a single rubber belt and iscontinuous over all of the core metal plates 21. The rubber belt 24includes no small thickness portion 25, which means that the rubber belt24 has the normal thickness portion. A surface of the core metal plate21 opposed to the link unit 12 is exposed from the rubber belt 24, andthe core metal plate 21 is directly welded to the link 13. The mud hole26 may be formed in the rubber belt 24 at a portion corresponding to themud hold 23 of the core metal plate 21. The mud hole 26 may notnecessarily be formed therein.

The manufacturing method according to the fourth embodiment of thepresent includes manufacturing the iron link belt 10, and manufacturingthe continuous pad 20.

During the manufacturing of the iron link belt 10, each of the coremetal plates 21 is welded to the pair of links 13 of each of theplurality of link units 12 of the link unit assembly 11.

During the manufacturing of the continuous pad 20, the rubber belt 24 isvulcanization-formed. At the time of vulcanization-forming, the smallthickness portion 25 is not formed in the rubber belt 24.

With the endless track and the manufacturing method thereof according tothe fourth embodiment of the present invention, since the rubber belt 24includes no small thickness portion 25, when the rubber belt 24 reachesthe sprocket of the construction vehicle, a greater force is requiredfor causing the rubber belt 24 to extend between adjacent core metalplates 21 than the first and the second embodiments of the presentinvention.

After the rubber belt 24 is vulcanization-formed such that the rubberbelt extends continuously over all of the core metal plates 21, therubber belt 24 may be divided or cut between two adjacent core metalplates of the core metal plates 21 into a plurality of separate pads. Inthat case, the manufacturing efficiency obtained by continuously formingthe rubber belt 24 over all of the core metal plates 21 can be improved,as compared with the conventional endless track in which the rubber padis vulcanization-formed per each of the core metal plates 21.

According to the present invention, the following technical advantagescan be obtained:

Since the vulcanization-forming of the single rubber belt to which aseries of core metal plates is embedded is performed simultaneously, theproductivity is greatly improved as compared with the conventionalendless tracks of the rubber pad type A and the rubber pad type B inwhich vulcanization-adhesion of rubber to each of core plates isconducted as many times as the number of the rubber pads.

Further, since a series of core metal plates is embedded to the singlerubber belt, the number of members required is smaller than that of theconventional endless tracks of the rubber pad type A and the rubber padtype B in which a plurality of rubber pads (core metal plates withrubber) need to be manufactured.

As discussed above, since the productivity improves by performingvulcanization-forming of the rubber belt simultaneously and the numberof members is reduced, the manufacturing cost of the endless track isreduced to nearly the same level as that of the conventional endlesstrack of the rubber crawler type.

Further, since the iron link belt bears the tensile force of the endlesstrack, the durability problem with the conventional endless track of therubber crawler type is completely eliminated. Thus, durabilitysubstantially the same as the conventional endless tracks of the rubberpad type A and the rubber pad type B can be obtained.

The foregoing description of the embodiments of the present inventionprovides illustration and description, but is not intended to beexhaustive or to limit the invention to the precise form disclosed.Modifications and variations are possible consistent with the aboveteachings or may be acquired from practice of the invention. Forexample, the various features of the invention, which are described inthe contexts of separate embodiments for the purposes of clarity, mayalso be combined in a single embodiment. Conversely, the variousfeatures of the invention which are, for brevity, described in thecontext of a single embodiment may also be provided separately or in anysuitable sub-combination. Accordingly, it will be appreciated by personsskilled in the art that the present invention is not limited to what hasbeen particularly shown and described hereinabove. Rather, the scope ofthe present invention is defined only by the attached claims and theirequivalents.

What is claimed is:
 1. An endless track comprising: an iron link beltincluding a link unit assembly constructed of a plurality of link unitsconnected to each other, each link unit including a pair of links; acontinuous pad including the same number of core metal plates as that ofsaid plurality of link units and a single rubber belt, each of said coremetal plates being fixed to each of said plurality of link units, saidrubber belt covering and being vulcanization-adhered to a groundopposing surface of each of said core metal plates, said rubber beltbeing continuous over all of said core metal plates; and a connectingdevice for connecting said iron link belt and said continuous pad atsaid link units and said core metal plates.
 2. An endless trackaccording to claim 1, wherein each of said pair of links comprises atleast one of a bent plate link and a forged link.
 3. An endless trackaccording to claim 1, wherein said connecting device comprises at leastone of a bolt-and-nut and a welding.
 4. An endless track according toclaim 3, wherein said connecting device comprises said bolt-and-nut, andsaid bolt-and-nut is welded to said core metal plate and is covered withrubber of said rubber belt.
 5. An endless track according to claim 1,wherein said iron link belt includes the same number of plates as thatof said plurality of link units, each of said plates being welded tosaid pair of links of each of said plurality of link units of said linkunit assembly and extending perpendicularly to a direction in which saidlink unit assembly extends, each of said core metal plates of saidcontinuous pad being fixed to each of said plates of said iron linkbelt, said rubber belt of said continuous pad including a smallthickness portion positioned between two adjacent core metal plates ofsaid core metal plates, said iron link belt and said continuous padbeing connected to each other by said connecting device at said platesand said core metal plates.
 6. An endless track according to claim 1,wherein each of said core metal plates of said continuous pad extendsperpendicularly to a direction in which said link unit assembly extendsand is directly welded to said pair of links of each of said pluralityof link units of said link unit assembly, said rubber belt of saidcontinuous pad including a small thickness portion between positionedtwo adjacent core metal plates of said core metal plates.
 7. An endlesstrack according to claim 1, wherein said iron link belt includes thesame number of plates as that of said plurality of link units, each ofsaid plates being welded to said pair of links of each of said pluralityof link units of said link unit assembly and extending perpendicularlyto a direction in which said link unit assembly extends, each of saidcore metal plates of said continuous pad being fixed to each of saidplates of said iron link belt, said rubber belt of said continuous padincluding a normal thickness portion positioned between two adjacentcore metal plates of said core metal plates, said iron link belt andsaid continuous pad being connected to each other by said connectingdevice at said plates and said core metal plates.
 8. An endless trackaccording to claim 1, wherein each of said core metal plates of saidcontinuous pad extends perpendicularly to a direction in which said linkunit assembly extends and is directly welded to said pair of links ofeach of said plurality of link units of said link unit assembly, saidrubber belt of said continuous pad including a normal thickness portionpositioned between two adjacent core metal plates of said core metalplates.
 9. A method for manufacturing an endless track comprising:connecting a plurality of link units each having a pair of links therebymanufacturing a link unit assembly of an iron link belt; and providingthe same number of core metal plates as that of said plurality of linkunits of said iron link belt and forming a single rubber beltcontinuously extending over all of said core metal plates such that saidsingle rubber belt covers and is vulcanization-adhered to a groundopposing surface of each of said core metal plates, therebymanufacturing a continuous pad.
 10. A method according to claim 9,wherein each link of said pair of links is manufactured through at leastone of a bending and forging process.
 11. A method according to claim 9,wherein during said manufacturing of an iron link belt, a plateextending perpendicularly to a direction in which said link unitassembly extends is welded to said pair of links of each of saidplurality of link units of said link unit assembly, and during saidmanufacturing of a continuous pad, before said core metal plates arefixed to said plurality of link units, a small thickness portion isformed between two adjacent core metal plates of said core metal plateswhen said rubber belt is vulcanization-formed, and after manufacturingsaid continuous pad, said iron link belt and said continuous pad areconnected to each other by a connecting device at said plates and saidcore metal plates.
 12. A method according to claim 11, wherein saidconnecting device includes a bolt and a nut, and before saidvulcanization-forming of a rubber belt, at least one of said bolt andsaid nut is welded to each of said core metal plate, and during saidvulcanization-forming of a rubber belt, at least one of said bolt andsaid nut is covered with a rubber of said rubber belt.
 13. A methodaccording to claim 9, wherein each of said core metal plates extendingperpendicularly to a direction in which said link unit assembly extendsis directly welded to said pair of links of each of said plurality oflink units of said link unit assembly of said iron link belt, and duringmanufacturing of said continuous pad, when said rubber belt isvulcanization-formed, a small thickness portion is formed to said rubberbelt between two adjacent core metal plates of said core metal plates.14. A method according to claim 9, wherein during said manufacturing aniron link belt, a plate extending perpendicularly to a direction inwhich said link unit assembly extends is welded to said pair of links ofeach of said plurality of link units of said link unit assembly, andbefore said manufacturing of a continuous pad, each of said core metalplates is fixed to said plate of each of said link units of said ironlink belt, and during said manufacturing of a continuous pad, saidrubber belt is vulcanization-formed such that said rubber belt coverseach of said core metal plates and such that a normal thickness portionis formed to said rubber belt between two adjacent core metal plates ofsaid core metal plates when said rubber belt is vulcanization-formed.15. A method according to claim 9, wherein each of said core metalplates extending perpendicularly to a direction in which said link unitassembly extends is directly welded to said pair of links of each ofsaid plurality of link units of said link unit assembly of said ironlink belt, and during said manufacturing of a continuous pad, a normalthickness portion is formed to said rubber belt between two adjacentcore metal plates of said core metal plates when said rubber belt isvulcanization-formed.
 16. A method according to any one of claims 14 or15 further comprising dividing said rubber belt between two adjacentcore metal plates of said core metal plates among a plurality ofseparate pads.